[ ak-sesh-uhn ]
See synonyms for accession on
  1. the act of coming into the possession of a right, title, office, etc.: accession to the throne.

  2. an increase by something added: an accession of territory.

  1. something added: a list of accessions to the college library.

  2. Law. addition to property by growth or improvement.

  3. consent; agreement; approval: accession to a demand.

  4. International Law. formal acceptance of a treaty, international convention, or other agreement between states.

  5. the act of coming near; approach.

  6. an attack or onset, as of a disease.

verb (used with object)
  1. to make a record of (a book, painting, etc.) in the order of acquisition.

  2. to acquire (a book, painting, etc.), especially for a permanent collection.

Origin of accession

1580–90; <Latin accessiōn- (stem of accessiō) an approach, addition. See access, -ion

Other words from accession

  • ac·ces·sion·al, adjective
  • non·ac·ces·sion, noun
  • re·ac·ces·sion, noun
  • un·ac·ces·sion·al, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use accession in a sentence

British Dictionary definitions for accession


/ (əkˈsɛʃən) /

  1. the act of entering upon or attaining to an office, right, condition, etc

  2. an increase due to an addition

  1. an addition, as to a collection

  2. property law

    • an addition to land or property by natural increase or improvement

    • the owner's right to the increased value of such land

  3. international law the formal acceptance of a convention or treaty

  4. agreement; consent

  5. a less common word for access (def. 2)

  1. (tr) to make a record of (additions to a collection)

Derived forms of accession

  • accessional, adjective

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012